The proposed research has as its goal a more complete understanding of children's cognitive development. Like adults, children may see complex forms, colors, and events. But unlike adults, children organize what they see in a simpler manner that is, perhaps, more directly controlled by the physical structure and limitations of basic information processing capabilities and the sensory system. Yet from these simple structures come the complex concepts, categories, and event interpretations of the adult. A new approach to understanding this developmental transition is described in this proposal, and the planned research bears on the accuracy of that new approach. That approach interprets young chilren's cognitive behavior as reflecting and understanding only of basic preceptual structures in the environment. For example, color is organized by young children in terms of the underlying perceptual dimensions of brightness, saturation, red-green hue, and blue-yellow hue. In contrast, older children have a "concept" of color defined by abstract relationships. Thus they are more likely to organized colors as "colors" and ignore conflicts with the basic pereptual dimensions of that attribute. These differneces mean that children younger that five years of age interpret and respond to tasks in a different manner than do older children and adults. This approach is contrasted with one that views the perception of some stimulus compounds as holistic and unitary (also called Integral) and other compounds as being susceptible to analysis and decomposition (also call Separable). This approach expects young children to view most stimuli and events as integral units and older children to be more capable of analyzing compounds and events. The experiments described in this proposal examine these differences in a series of concept sorting tasks, discrimination learning tasks, and tasks in which values of various attributes are compared. In addition, the validity of the two developmental models is evaluated. Support for one of these models vis-a-vis the other will enable developmental psychologists to more fully understand and plan for children's cognitive devlopment.